Menene manyan nau’ikan tubali masu ratsa jiki ta fuskar kamanni da siffa?

Ana iya raba bulogi masu jujjuyawa zuwa kashi biyu daga bayyanar da siffa:

① Ƙwararren tubali na musamman, siffar bayyanar ita ce concave-convex surface, siffar da ba ta dace ba, tare da gefuna da sasanninta, ramukan zagaye ko arcs, kuma siffar na iya zama cylindrical ko trapezoidal.

②Bulogin da aka saba amfani da su, kamar nau’ikan nau’ikan nau’ikan T-size na gama gari, bulogi mai girman G-size da bulogin kiln bulo, suna da fayyace ma’auni masu girman gaske kuma ana kiran su tubalin da aka saba amfani da su. Kowane nau’i na tubali na refractory yana samar da kayan abu daban-daban da siffofi da girma, don haka duk sun bambanta, nau’in tubali guda ɗaya yana da nauyin iri ɗaya.